( function () {
/**
 * Luminosity
 * http://en.wikipedia.org/wiki/Luminosity
 */
const LuminosityShader = {
  uniforms: {
    'tDiffuse': {
      value: null
    }
  },
  vertexShader:
  /* glsl */
  `

		varying vec2 vUv;

		void main() {

			vUv = uv;

			gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );

		}`,
  fragmentShader:
  /* glsl */
  `

		#include <common>

		uniform sampler2D tDiffuse;

		varying vec2 vUv;

		void main() {

			vec4 texel = texture2D( tDiffuse, vUv );

			float l = linearToRelativeLuminance( texel.rgb );

			gl_FragColor = vec4( l, l, l, texel.w );

		}`
};

THREE.LuminosityShader = LuminosityShader;
} )();
